Acton Municipal Utility District

GRAVITY SANITARY SEWER MATERIALS AND CONSTRUCTION

1.0          APPLICABLE PUBLICATIONS:

The following publications forma part of these specifications to the extent indicated by references thereto. Only the most recent revisions of these publications shall be used.

1.1          American Society for Testing and Materials (ASTM):

1.2          American National Standards Institute (ANSI):

2.0          GENERAL:

Gravity sanitary sewer construction shall include the furnishing and installation of pipe, joint materials, appurtenances Such as manholes and connections to the existing system as required.

2.1          Size and Slope:

The minimum size gravity sanitary sewer shall be 6-inch.  All gravity sanitary sewers shall be designed and constructed with hydraulic slopes sufficient to give a velocity of between 2 feet per second and 10 feet per second. The grades shown in the following table shall be minimum acceptable slopes:

2.2          Alignment:

All gravity sanitary sewers shall be laid in a straight horizontal and vertical alignment between manholes.

2.3          Manhole spacing:

Maximum spacing between manholes shall be 400 feet.  Manholes shall be constructed at all changes in alignment, slope, pipe diameter, pipe junctions and at the end of all sewer lines.

3.0          MATERIALS:

Materials shall conform to the respective specifications and other requirements specified below:

3.1          Vitrified clay pipe:

The pipe shall conform to all the requirements of ASTM  700 for extra strength clay pipe. Maximum pipe lengths produced by the manufacturer shall be furnished, except for fittings, closures and specials.

3.1.1       Joints:

Compression joints for vitrified clay bell and spigot pipe shall conform to the requirements of ASTM C 425. Compression couplings f or clay plain-end pipe shall conform to the requirements of ASTM C 594, Type B.

3.1.2       Fittings:

Fittings shall be monolithic type conforming to the requirements of ASTM C 700.

3.1.3       Embedment:

Embedment shall be granular with a maximum size of 314' . Embedment shall include the area around the pipe from a point 3 inches below the pipe to 6 inches above the top of the pipe.  Embedment in rock trenches shall include an additional 3 inches beneath the pipe.

3.2          PVC sewer pipe:

Poly (Vinyl Chloride) (PVC) sewer pipe shall conform to the requirements of ASTM D 3034 Pipe and fittings shall be made of PVC plastic compound conforming to ASTM D 1784 as required by ASTM D 3034.

3.2.1       Wall thickness:

The minimum wall thickness shall be that resulting from a Standard Dimensional Ratio (SDR) of 35, except for 4" diameter pipe which shall be SDR 33.5.

3.2.2       Joints:

Joints for pipe and fittings shall be of the Elastomeric gasket type conforming to ASTM F 477.

3.2.3       Embedment:

Embedment shall be granular with a maximum size of 3/4". Embedment shall include the area around the pipe from a point 3 inches below the pipe to 6 inches above the top of the pipe. Embedment in rock trenches shall include an additional 3 inches beneath the pipe.

3.3          Ductile iron pipe:

All ductile iron pipe shall be designed in accordance with ANSI A 21.50.  Ductile iron pipe shall conform to ANSI A 21.50.  Ductile iron pipe shall conform to ANSI A21.21.

3.3.1       Wall thickness:

Minimum wall thickness class shall be as determined by the applicable tables of the specified ANSI standards for ductile iron pipe. Pipe shall be suitable for trench conditions and depths as shown on the drawings and specified herein.

3.3.2       Joints:

Push on joints shall conform to ANSI  A 21.11 with neoprene or synthetic rubber gaskets.

3.3.3       Fittings:

Ductile iron fittings shall be designed in accordance with and shall conform to ANSI A 2 1. 10.

3.3.4       Lining:

Ductile iron pipe shall be lined with cement mortar in accordance with ANSI A 21.4. Bituminous coatings shall be manufacturer's standard.

3.3.5       Embedment:

Embedment shall be select backfill. Embedment shall include the area around the pipe from a point 3 inches below the pipe to the pipe centerline. Rock trenches shall include an additional 3 inches of embedment beneath the pipe.

3.4          Sleeves:

All sleeves installed in bored or tunneled holes shall be steel pipe conforming to ASTM A 53. Unless shown otherwise on the drawings, steel sleeves shall have the following minimum all thickness.

3.5          Manholes:

Manholes may be constructed of brick, precast concrete with developed base or precast concrete without developed base. Manhole materials shall conform to the following:

3.5.1       Brick manholes:

Brick shall conform to ASTM C 32, grade MS. Mortar for brick manhole construction shall conform to ASTM C 270, Type M.

3.5.2       Precast concrete manholes without developed base:

The precast concrete manholes shall conform to ASTM C 478. Joints between the riser sections shall be "0" ring joints conforming to ASTM C 443 or a double gasketed joint of flexible butyl rubber joint sealant.

3.5.3       Precast concrete manholes with developed base:

The precast concrete manhole shall conform to ASTM C 478. The developed base shall be poured monolithic with the bottom riser section. The base reinforcement shall be continuous with the reinforcement of the bottom riser section. The diameter of the base shall be 8 inches larger than the outside diameter of the bottom riser section. Joints between the riser sections shall be "0" ring joints conforming to ASTM C443 or a double gasketed joint of flexible butyl rubber joint sealant. Pipe opening shall be furnished with cast‑in‑place flexible entrance seals. ALOK flexible seals manufactured by A LOK corporation or Press Wedge II manufactured by Press‑Seal Gasket Corporation are approved.

3.5.4       Castings:

Manhole rings and lids shall be constructed of gray cast iron conforming to ASTM A 48. Castings for standard and shallow manholes shall be Bass and Hays Foundry, Pattern 300‑24 manhole ring and cover.

3.5.5       Protective coating:

The protective coating for the exterior of manholes shall be Koppers Company, Inc. Bitumastic No. 50 or Tnemec Company, Inc. asphalt base foundation coat. Brick manholes shall be field coated. Precast manholes shall be shop coated.

4.0          INSTAILLATION:

4.1          General:

All pipe, fittings and other accessories shall be carefully lowered into place, piece by piece, by means of derrick ropes or other suitable tools or equipment, in such manner as to prevent damage to pipe.  Under no circumstances shall pipe or accessories be dropped or dumped.  Before lowering and while suspended, the pipe shall be inspected for defects. Any defective, damaged or unsound pipe shall be removed from the job site. All foreign matter or dirt shall be removed from the inside of the pipe before it is placed in position and it shall be kept clean by approved means during and after installation.

4.2          Pipe laying:

Pipe laying shall proceed upgrade with the spigot end of the pipe pointing in the direction of f low. Pipe shall be laid so that the sewer has a uniform invert, All exposed ends and openings to the pipe shall be suitably protected at all times and shall be closed to keep out all foreign matter. Only the "working end" of the line shall be open while pipe is being laid. A "night cap" shall be provided and kept in the end of the line at ALL times when pipe laying is not in progress.

4.2.1       Vitrified clay pipe:

Installation of vitrified clay pipe shall conform to ASTM C 12.

4.2.2       PVC sewer Pipe:

Installation of PVC sewer pipe shall conform to ASTM D 2321, Installation of PVC slip-on joint pipe shall be made by thoroughly brushing and cleaning the bell of the previously laid section and the spigot of the section to be laid. After which the bell, spigot and the rubber gasket shall be properly lubricated. The gaskets and lubricant shall be as recommended and supplied by the pipe fabricator. The lubricated gasket shall then be positioned in the groove of the bell‑end of the pipe after which the spigot-end shall be entered into the bell of the previously laid pipe and carefully centered. The joint shall then be pushed "home".

4.2.3       Ductile iron slip-on joint piping:

Installation of slip-on joint ductile iron pipe shall be made by thoroughly brushing and cleaning the bell of the previously laid section and the spigot of the section to be laid, after which the bell, spigot and the rubber gasket shall be properly lubricated. The gaskets and lubricant shall be as recommended and supplied by the pipe fabricator. The lubricated gasket shall then be positioned in the groove of the bell‑end of the pipe after which the spigot-end shall be entered into the bell of the previously laid pipe and carefully centered. The joint shall then be pushed "home".

4.3          Sleeves:

Joints of the steel sleeve installed in the tunnel or bored hole shall be made by full butt welds, After the sleeve is placed in the tunnel or bored hole, all void spaces between the steel sleeve and surrounding soil shall be completely filled with Portland cement grout.

4.4          Pipe in sleeves:

Each end of each joint of pipe shall be protected prior to insertion into the sleeve, to prevent abrasion damage. The pipe may be installed in the sleeve either by jacking or by pulling with a cable.  The end of the pipe shall be protected f or jacking or pulling by the use of heavy  timbers or other suitable pads.

4.5          Manholes:

Manholes shall be constructed of brick or precast concrete rings, with cast iron frames and covers as specified herein. The invert channels shall be smooth and semicircular in shape conforming to the inside of the adjacent sewer section. Changes in direction of flow shall be made with a smooth curve of as large a radius as the size of the manhole will permit. Changes in size and grade of the channels shall be made gradually and evenly. The invert channels shall be formed directly in the concrete of the manhole base. The floor of the manhole outside the channels shall be smooth and shall slope toward the channels not less than 1-inch per foot nor more than 2 inches per foot.

4.5.1       Brick manholes:

Brick manholes shall be constructed on a cast‑in‑place concrete foundation slab. Mortar joints shall be completely filled and shall be smooth and free from surplus mortar on the inside of the manhole. Manholes shall be plastered with 1/2 inch of mortar over the entire outside surface of the walls. Brick shall be laid radial with every sixth course laid as a stretcher course. Pipe connection to the manholes for all pipe, except iron, shall be made by placing a tight fitting rubber gasket around the outside of the pipe where the pipe enters the manhole.  And then filling Road & Highway Crossings the void between the gasketed pipe and the manhole wall with non-shrink grout. The gasket shall be omitted for iron pipe. The exterior of the manholes shall be painted with two coats of protective coating to a total dry film thickness of 17-24 mils. The method of application shall conform to the recommendations of the paint manufacturer.

4.5.2       Precast concrete manholes without developed base:

Precast concrete manholes without a developed base shall be constructed on a cast‑in‑place concrete foundation slab. Pipe connection to the manholes for all pipe except iron shall be made by placing a tight fitting rubber gasket around the outside of the pipe where the pipe enters the manhole and then filling the void between the gasketed pipe and the manhole wall with non‑shrink grout. The gasket shall be omitted for iron pipe. Gasketed joints between each riser section shall be installed in strict conformance with manufacturer's recommendations. Damaged exterior coating shall be field touched up prior to backfilling.

4.5.3       Precast concrete manholes with a developed base:

Precast manholes, with a developed base, shall be placed on a crushed rock base. The crushed rock base shall be graded smooth, level and to the correct grade. The bottom riser section shall be placed upon the crushed rock base and checked for alignment, elevation and plumbness. If not correct, the bottom riser section shall be completely removed from the excavation and the crushed stone base reshaped. Pipe connections to the manholes shall be in strict conformance with manufacturer's instructions for installation of the flexible entrance seals. Gasketed joints between each riser section shall be installed in strict conformance to manufacturer's recommendations. Damaged exterior coating shall be field touched up prior to backfilling.

4.5.4       Frames and covers:

Unless shown otherwise on the drawings, all castings shall be set f lush with finish grade in all roadways, 2 inches above grade in lawns, and at least 12 inches above finish grade in all other areas.

4.5.5       Connections to existing manholes:

Pipe connections to existing manholes shall be made in such manner that the finish work will conform to the essential applicable requirements specified for new manholes, including all necessary concrete work, cutting and shaping. 

5.0          Acceptance Tests:

Prior to acceptance of the sewers, both visual inspection and leakage tests must be satisfactorily completed.  Inspections and testing shall be completed in the presence of a District inspector.  Tests shall not be performed until after the completion of the installation of pipe and appurtenances and backfill of the trench.

5.1          Visual inspection:

All sewers shall be inspected to determine the presence of any misalign, displaced or broken pipe, any excessive pipe deflection, any infiltration or any other physical defects. All defects shall be satisfactorily corrected prior to conducting leakage tests.

5.2          Leakage tests:

All sewers shall be tested for leakage by use of water or air, at the Developer's option. Only one of the methods (water or air) shall be used throughout the project.

5.2.1       Water leakage test:

If the ground water level is at least 2 feet above the top of the sewer pipe, infiltration leakage test shall be used. If the ground water level is below 2 feet above the pipe, Exfiltration test shall be used,

5.2.1.1    Infiltration leakage test procedure:

Infiltration leakage test shall be performed on a] I sewer pipe when the ground water level is at least 2 feet above the top of the pipe. The test shall be maintained as long as necessary to locate all leaks, but not less than 2 hours. Repeat as necessary after repairs until measured leakage does not exceed 0. 15 gallons per inch of internal diameter per hour per 100 feet of pipe length (200 gallons/inch I.D./day/mile).

5.2.1.2    Exfiltration leakage test procedure:

Exfiltration leakage test shall be performed on all sewer pipe when the ground water level is below 2 feet above the top of the sewer pipe. Exfiltration tests shall be performed with not less than 2 feet of head above the top of the pipe or above the water table, whichever is higher. The test shall be maintained as long as necessary to locate all leaks, but not less than 2 hours. Repeat as necessary after repairs until measured leakage does not exceed 0. 15 gallons per inch of internal diameter per hour per 100 feet of pipe length (200 gallons/inch I.D./day/mile). Protect manholes and other structures by means of bulkheads to prevent bursting pressures from being applied to the inside surfaces of structures. Dewater pipe upon completion of testing.

5.2.2       Air leakage test:

All testing equipment including pipe and pipe connections, test pumping equipment, pressure gauges, bulkheads, pressure regulators and other materials and equipment shall be furnished. The length of line tested with one specific test shall be between manholes or structures.

5.2.2.1    Testing equipment:

All testing equipment used for air tests shall be standard equipment and materials except pressure gauges. Pressure gauges shall be 6 inch diameter with 0 to 15 psig range, I psig figure intervals, 0.05 psig minor subdivisions, bronze Bourdon tube, nylon or stainless steel movement and an accuracy within 0.25% of full scale range.

5.2.2.2    Test procedure:

Plug ends of line and cap or plug all connections to withstand internal pressure. A tap installed in a pipe plug shall make the test connection. After connecting air control equipment to the air hose, monitor air pressure so that internal pressure does not exceed 5.0 psig. After reaching 4.0 psig, throttle the air supply to maintain between 4.0 and 3.5 psig for at least 2 minutes in order to allow equilibrium between air temperature and pipe walls. During this time, check all plugs to detect any leakage. If plugs are found to leak, bleed off air, tighten plugs, and again begin supplying air. After temperature has stabilized, the pressure is allowed to decrease to 3.5 psig. At 3.5 psig, begin timing to determine the time required for pressure to drop to 2.5 psig. If the time, in seconds, for the air pressure to decrease from 3.5 psig to 2.5 psig is greater than that shown in the following table, the pipe shall be presumed free of defects.

If air test fails to meet above requirements, repeat test as necessary after all leaks and defects have been repaired. In areas where there is ground water the test shall be performed at 3.5 psi above the ground water head exerted to the top of the sewer pipe.

5.3          Deflection test:

All poly (vinyl chloride) sewer pipes shall be tested by pulling a mandrel through the entire length thereof. The test shall be conducted not less than one month after backfill has been properly installed.  The maximum allowable deflection shall not exceed five percent of the pipe's base inside diameter.  The diameter of the mandrel] shall be five percent less than the base inside diameter of the pipe.

Any pipeline found not conforming to these requirements shall be replaced.

6.0          SUBMITTALS:

The Developer-Contractor shall submit certified statements for material manufacturing and testing for all material. This statement shall certify that ALL material conforms to these specifications.

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Copyright © 2004-2007 Acton Municipal Utility District
Last modified: November 26, 2008